>>31163879Prediction works both ways. If you're so sure about using your one time move, then go ahead and do it. But if you're not sure, or just happen to be playing with an experienced trainer, maybe it might be more worth your time to just run a Life orb to deal more consistent damage each time.
Sure, it might work nicely once in a while but once in a while isn't consistent enough.
Idk, I don't see Z-moves making much of a difference or an impact on the meta. Maybe Z status moves.